McQueary also told the team he's not at the University, but in protective custody after receiving several threats ... and "double fisting" booze.

McQueary was placed on administrative leave earlier today.

McQueary -- who's married with a 2-year-old daughter -- is the man who witnessed Jerry Sandusky allegedly rape a young boy back in 2002 ... but failed to stop the attack and didn't report the crime to the police.